Analysis and characterization of real catalysts using ion beam analysis

The aim of this work is to present the potentialities of IBA techniques in the characterization of catalytic precursors, real catalysts, supports and products of catalyzed reactions of industrial interest. RES was used in the study of photochemical reactions of metal carbonyls with triphenylphosphine in the presence of alumina in order to follow the metal loadings on the alumina surface as a function of the irradiation time. In the characterization of Zr metallocene catalysts with Al based cocatalysts supported on silica, both RES and NRA were used. The first technique allowed the determination of the adsorption isotherms of incorporated Zr/SiO2 ratios as a function of the initial ratios in the solutions, for different kinds of commercial silica powders. Using the Al-27(p,gamma)(28) Si nuclear reaction, the Al/SiO2 incorporated ratios were obtained as a function of the initial ratios in the solutions of two different cocatalysts. IBA techniques were also used in the study of polymerization reactions and in the characterization of the polymers produced by reactions which used V based catalysts. From the RES spectra the stoichiometry of the resulting polymers, their degree of contamination with the catalysts, as well as the metal catalyst distribution profile in industrially produced polymer pellets were determined. In the environmental protection field the synthesis steps of W, Pd and alumina based automobile exhaust converters were successfully followed by RES. This technique was also very useful to determine the products of the thermal decomposition of bimetallic compounds derivative from diphenylphosphineferrocene (dppf). Finally, RES played a key role in the confirmation of the stoichiometry of cationic nickel (II) complexes synthesized either chemically or electrochemically. (C) 1998 Elsevier Science B.V.